The present invention relates to implantable hemodynamic monitors (IHMs). Specifically, the invention relates to systems that interface with various hospital monitoring systems to transfer data from the IHMs to doctors and other data processing centers. More specifically, the invention pertains to heart failure data management systems that provide a concise and reliable summary view of information in a manner that is useful for clinicians and health care personnel to monitor, assess, evaluate and treat heart failure conditions in patients. Further, the invention pertains to a system of a bi-directional communication system that is network, Internet, intranet and worldwide web compatible to enable chronic monitoring based on data obtained from the IHMs.
The need to monitor, on a frequent and continuous basis, the vital signs associated with hospitalized patients particularly those who are seriously ill is an important aspect of health care. Virtually every hospitalized patient requires periodic measurement in logging of blood pressure, temperature, pulse rate, etc. Such monitoring has typically been performed by having a health care worker periodically visit the bedside of the patient and measuring and/or observing the patient""s vital signs using dedicated equipment that is either hooked up to the patient or brought into the patient""s room. Such a monitoring procedure is not ideally cost-effective because of its being highly labor intensive.
A great many implantable medical devices (IMDs) for cardiac monitoring and/or therapy whose sensors are located in a blood vessel or heart chamber and coupled to an implantable monitor or therapy delivery device are used for diagnosis and therapy. Such systems include, for example, implantable heart monitors, therapy delivery devices, and drug delivery devices. All these systems include electrodes for sensing and sense amplifiers for recording and/or deriving sense event signals from the intracardiac electrogram (EGM). In current cardiac IMDs that provide a therapy, sensed event signals are used to control the delivery of the therapy in accordance with an operating algorithm. Selected EGM signal segments and sensed event histogram data or the like are stored in an internal RAM for telemetry to be transmitted to an external programmer at a later time. Efforts have also been underway for many years to develop implantable physiologic signal transducers and sensors for temporary or chronic use in a body organ or vessel usable with such IHMs for monitoring a physiologic condition other than, or in addition to, the disease state that is to be controlled by a therapy delivered by the IMD.
A comprehensive listing of implantable therapy devices are disclosed in conjunction with implantable sensors for sensing a wide variety of cardiac physiologic signals in U.S. Pat. No. 5,330,505, incorporated herein in its entirety by this reference.
Typically, an IHM measures blood pressure and temperature signal values which stem from changes in cardiac output that may be caused by cardiac failure, ventricular tachycardia, flutter or fibrillation. These variations may reflect a change in the body""s need for oxygenated blood. For example, monitoring of a substantial drop in blood pressure in a heart chamber, particularly the right ventricle, along or in conjunction with an accelerated or chaotic EGM, was proposed as an indicator of a fibrillation or tachycardia sufficient to trigger automatic delivery of defibrillation or cardioversion shock. More recently, it has been proposed to monitor the changes in blood pressure by comparing those values that accompany the normal heart contraction and relaxation to those that occur during high-rate tachycardia, flutter or fibrillation.
A number of cardiac pacing systems and algorithms for processing monitored mean blood pressure or monitored dp/dt have been proposed and in some instances employed clinically for treating bradycardia. Such systems and algorithms are designed to sense and respond to mean or dp/dt changes in blood pressure to change the cardiac pacing rate between an upper and a lower pacing rate limit in order to control cardiac output. Examples of IHMs blood pressure and temperature sensors that derive absolute blood pressure signals and temperature signals are disclosed in commonly assigned U.S. Pat. Nos. 5,368,040, 5,535,752 and 5,564,434, and in U.S. Pat. No. 4,791,931, all incorporated by reference herein.
The Medtronic(copyright) Chronicle(trademark) Implantable Hemodynamic Monitor (IHM) disclosed in U.S. Pat. Nos. 6,024,704 and 6,152,885, both incorporated herein by reference in their totality, employ the leads and circuitry disclosed in the above-incorporated commonly assigned U.S. Pat. Nos. 5,535,752 and 5,564,434 patents to record absolute blood pressure values for certain intervals. The recorded data is transmitted to a programmer under the control of a physician in an uplink telemetry transmission from the IHM during a telemetry session initiated by downlink telemetry transmission from the programmer""s radio frequency (RF) head and receipt of an integration command by the IHM. Thus, in accordance to the ""704 and ""885 patents, a method is disclosed in which an IHM is used for deriving reference and absolute pressure signal values using implantable physiologic sensors to detect relative cardiac pressure signal values for storage and transmission.
Further, in accordance with the ""704 and ""885 patents, calibration of the reference pressure and/or temperature sensors in relation to an external calibrated barometric pressure and/or body temperature sensors could be accomplished. In addition, the same system may be used to interlace digital signal values related to pulmonary artery diastolic pressures with the primary cardiac pressure signal values derived from the right ventricle as disclosed in U.S. Pat. No. 6,155,267, incorporated herein by reference.
Heart failure is a progressive disease. While treatment slows the progression of the disease, current technology does not provide a cure. The best treatment regimen available to date is a combination of continuous diagnosis and drug therapy. Once a heart failure patient is in the hospital, current technology does not provide a continuous means of monitoring the patient during their stay in the hospital. Current practice is based on a dedicated programmer that is used to gain access to the pressure waveforms. Only trained physicians can currently uplink the data, and this is available only when such a trained physician is present, and is therefore not available on a continuous basis.
The present invention enables continuous remote monitoring of patients. In sharp contrast, prior heart failure management involves taking measurements of a few variables in the clinic with accurate catheterization pressures taken only occasionally because of the difficulty of obtaining them.
Accordingly, there is a need to provide continuous and reliable measurements over sustained long period of time. Further, emerging trends in health care including remote patient management systems require that the IMD/IHM be compatible with communication systems, including the Internet, the worldwide web, and similar systems to provide real-time communications and data exchange between the IHM in a patient and a remote center where physicians and other experts reside.
The present invention relates to chronic data management for cardiac systems. Specifically, the invention pertains to IHMs that monitor heart failure. In its broader aspect, the invention relates to patient management that enables the collection of chronic data for remote patient management, including remote delivery of clinical diagnosis and therapy.
Yet another aspect of the invention includes a user-friendly screen-displayable data management system that presents clinically relevant measurements. Another aspect of the invention provides a software system that enables the translation and transposition of IHM collected data to be presented to a clinician in a manner to enable efficient and reliable evaluation of patient conditions remotely.
The invention further relates to data reduction in a monitoring system as generally disclosed in co-pending application entitled xe2x80x9cImplantable Medical Devices Monitoring Method and System Regarding Samexe2x80x9d filed on Dec. 15, 1999, U.S. application Ser. No. 09/992,978, incorporated herein by reference in its entirety.
The present invention, inter alia, enables the transfer of a patient""s medical data to one or more monitoring stations staffed by expert personnel to have access to the data in real time. Although the IHM device implemented in the present invention relates to the measurement of cardiac pressure, other IHM devices that detect and transmit additional physiological signals such as oxygen saturation, pulmonary artery diastolic and systolic pressure, temperature and related data may be used as the originating device or data source. Transferring real-time signals from IHMs to various physician portals and locations provides a highly accentuated medical service and effective chronic monitoring of patients.
In one aspect of the present invention an IHM device determines the hemodynamic status of a patient from measurement of pulmonary pressure and right atrial pressure obtained from a single absolute pressure sensor implanted in the right ventricle. Both of these values have been shown to correlate to the degree and extent of cardiac failure of a patient. The IHM continually monitors the right ventricular pressure using an absolute pressure sensor and marks the right ventricular pressure at the moment of specific events.
One aspect of the present invention is to provide a means by which physicians could view data available via real-time telemetry other than using a local data retrieving system, such as a programmer. Currently, physicians use the programmer to view the real-time pressure wave along with the EGM tracing. Using the present invention, the IHM device would be able to telemeter real time signals to a system via a programmer or other instrument to a remote location.
Another aspect of the present invention relates to the presentation of data from IHMs in a summary view that""s useful and familiar to clinicians and patients. Yet another aspect of the present invention includes a process by which data is collected by IHMs, which data includes but is not limited to heart rate patient activity and pressure data, to establish that the patient is in a state of repeatable data routine on a daily basis. For example, this might mean application of a magnet when the patient is lying down, or using devices such as time-of-day counters, activity sensors, posture sensors, etc. Such data is retrieved for analysis via home monitors, programmers or similar devices, and the data sent over an Internet/intranet, worldwide web or a similar network to a remote location for analysis by clinicians or for storage and archiving at a Medtronic server.
The data is processed for collection with past pull-up records to compose a continuous patient record. Specifically, clinically relevant measurements are pulled out of the data. This would mean observing the average values measured during a daily test, including, for example, the patient reclining for 5 minutes. These values and the deviation or change are compared against clinical norms and flagged for the user if they are abnormal. For example, color plus footnote designations may be used to identify or flag abnormal data. Other variations such as italics, specialized fonts, bigger fonts, e-mail reports, faxed reports may be used to identify deviations from normal clinical data or established chronological data for the patient. The clinical norms can optionally be modified for each patient by the clinician and then serve as a clinical baseline for the particular patient.
One other aspect of the present invention is the display of data which without limitation, includes the most recent daily test data along with data from the previously interrogated data. A comparative value between the two and a previous interrogation date to compare collected data with chronological data are used.
Yet another aspect of the present invention includes a single page view of chronic heart failure status, translation of raw data into clinical indicators of heart failure status, analysis of changes in indicators over a user-selectable time period, flags and indicators to identify changes that are outside of clinical norms, tailoring of graphical displays and data management to a patient""s clinical norms, means to determine if the patient is in a state of repeatable condition from day to day, and automated data analysis triaging which provides a foundation for further data analysis and automation.